I am not an expert on this subject matter but I suspect much of the required structure for younger kids is only a necessity due to constant restrictions and monitoring that's been put in place by modern society. In other words, we are not giving enough space to develop on their own terms and explore their surroundings.

I grew up in the 80s and 90s and remember spending a lot of time unsupervised going about wherever and doing all sorts of wild things well before I was 7 years old. Looking back now as a parent it is absolutely terrifying to me what I was "allowed" to do. Then again when I think about the Norma in countries like Japan (where it is not uncommon to see kindergarten kids walking home by themselves and crossing streets and intersections), I am reminded that kids can develop independently to a great tune than we give them credit for. I don't know about Japanese kids materials levels but I've noticed that they are typically given more freedoms to act independently and spend a lot more time on outdoor and social activities. If I had to guess I'd say they are a lot less materialistic than their Western counterparts.

As for my own child, I try to let him be independent even at 1 year. For example, we have a TV stand that any parent would be terrified if their kid climbed on it. I was terrified at first but then with some observation and secret supervision I let him climb it. To my surprise he quickly learned how to turn around and get down safely. There was only a single time when he fell from it sideways unhurt, but now he goes up and down like a pro without any supervision. I can leave the room knowing he will always get down fine. To what effect independence will have an impact on materialism remains to be seen but I suspect one of the commenters is right on the money with mirroring behavior and values.